This application relates generally to acoustic probes and systems. More specifically, this application relates to methods and apparatus for testing acoustic probes and systems.
Acoustic imaging techniques have been found to be extremely valuable in a variety of applications. While medical applications in the form of ultrasound imaging are perhaps the most well known, acoustic techniques are more generally used at a variety of different acoustic frequencies for imaging a variety of different phenomena. For example, acoustic imaging techniques may be used for the identification of structural defects, for detection of impurities, as well as for the detection of tissue abnormalities in living bodies. All such techniques rely generally on the fact that different structures, whether they be cancerous lesions in a body or defects in an airplane wing, have different acoustic impedances. When acoustic radiation is incident on an acoustic interface, such as where the acoustic impedance changes discontinuously, it may be scattered in ways that permit characterization of the interface. Radiation reflected by the interface is most commonly detected in such applications, but transmitted radiation is also used for such analysis in some applications.
Transmission of the acoustic radiation towards a target and receipt of the scattered radiation may be performed and/or coordinated with a modern acoustic imaging system. Many modern such systems are based on multiple-element array transducers that may have linear, curved-linear, phased-array, or similar characteristics. These transducers may, for example, form part of an acoustic probe. In some instances, the imaging systems are equipped with internal self-diagnostic capabilities that allow limited verification of system operation, but do not generally provide effective diagnosis of the transmission and receiving elements themselves. Degradation in performance of these elements is often subtle and occurs as a result of extended transducer use and/or through user abuse.
In particular, because modern acoustic systems form images by adding up the contributions of many transducer elements from transducer arrays, the failure of a small number of elements, or a few defective receive channels in the acoustic system, may not be readily perceptible to users. This is a consequence of the averaging effect of summing many elements to form an acoustic beam. But the failure of a small number of elements or receive channels can, nonetheless, significantly degrade the performance of an imaging system, especially in a Doppler mode.
There is accordingly a general need in the art for a convenient, inexpensive, and easy-to-use method for evaluating acoustic probes and systems for failed elements or transmit and receive channels.